Radeon HD 4850 1GB vs Radeon HD 6950 2GB

Intro

Compare those specifications to the Radeon HD 6950 2GB, which comes with GPU core speed of 800 MHz, and 2048 MB of GDDR5 memory set to run at 1250 MHz through a 256-bit bus. It also features 1408 Stream Processors, 88 Texture Address Units, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4850 1GB		110 Watts
Radeon HD 6950 2GB		200 Watts
	Difference: 90 Watts (82%)

Memory Bandwidth

In theory, the Radeon HD 6950 2GB should be a lot faster than the Radeon HD 4850 1GB overall. (explain)

Radeon HD 6950 2GB		160000 MB/sec
Radeon HD 4850 1GB		63552 MB/sec
	Difference: 96448 (152%)

Texel Rate

The Radeon HD 6950 2GB will be much (approximately 182%) more effective at texture filtering than the Radeon HD 4850 1GB. (explain)

Radeon HD 6950 2GB		70400 Mtexels/sec
Radeon HD 4850 1GB		25000 Mtexels/sec
	Difference: 45400 (182%)

Pixel Rate

The Radeon HD 6950 2GB will be quite a bit (approximately 156%) more effective at AA than the Radeon HD 4850 1GB, and also able to handle higher screen resolutions better. (explain)

Radeon HD 6950 2GB		25600 Mpixels/sec
Radeon HD 4850 1GB		10000 Mpixels/sec
	Difference: 15600 (156%)

Please note that the above 'benchmarks' are all just theoretical - the results were calculated based on the card's specifications, and real-world performance may (and probably will) vary at least a bit.

Price Comparison

Specifications

Memory Bandwidth: Bandwidth is the largest amount of data (in units of MB per second) that can be moved past the external memory interface within a second. It is worked out by multiplying the bus width by its memory clock speed. If it uses DDR type memory, the result should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are applied in one second. This is calculated by multiplying the total number of texture units of the card by the core speed of the chip. The better the texel rate, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip can possibly record to its local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the amount of Raster Operations Pipelines by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.